I have a 99 cavalier rs with a cold air intake, stainless steel header, magnaflow high flow cat, and a cat back exhaust, I bought brand new bosch oxygen sensors when I put my exhaust on. Now I'm throwing a check engine light with the code saying system running too lean. My question now is do I need to get my ecu tuned, or do I need to get bigger injectors, or turn up fuel pressure to get that back in to specs? I also have an air/fuel ratio gauge set up in the car and you can tell its running lean. I just want the check engine light off and it running back in specs.
BeeFinn56
Maybe you already have, but I would try some simple things first like fuel filter or vac leaks. After that I would go fuel pressure and volume. Maybe even check your fuel trim values on the scantool. I'm not exactly sure what your specs are but I am sure somebody will chime in
those Bosch 02 sensors are crap. get yourself a Denso 02
Rich Grayo Jr. wrote:wideband or narrowband a/f ratio gauge?
wondering this myself
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narrowband a/f gauge i believe and ive never had any problems with any bosch product, considering i bought them to replace @!#$ty ebay sensors, ill stick with the bosch, i dont think i have a vacuum leak since before i put the exhaust on it was running slightly rich, after i put the exhaust on now its way too lean. it seems like its too lean close to or at idle and at cruise it is only slightly lean, like it can compensate better with the rpm increase, which makes sense. i think i just helped it breath so much that now its starved for fuel. i just dont know which route i should go now if i should get aftermarket injectors, an adjustable fuel pressure regulator, and/or ecu tune or any combo of those. my friend was saying they dont make injectors small enough to just get me back to normal a/f ratio that the smallest i could get would be like 600cc or something. what size are the stock ones? and does anyone have a solution to this aftermarket problem?
Those bolt on's are not going to be enough to lean your car out that much. Something else is going on, and I'd listen to these guys on the O2 sensors. More than likely you have a sensor that's bad.
The narrowband is just a light show. It has no resemblance to something that could be used as a real gauge.if this is what you're using to tell you that you're running rich/lean, then ignore it. Also, it's fairly well documented that these cars don't behave well with bosch o2 sensors. Delco or bust.
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